Stoker



se uls; 1945.

H. E. PRESTON smoxmz Filed Oct. 29. 1941' 6 Sheets-$11661. 1

INVENTOR HERBERT E P ESTON Ill l nrllll l ATTORNEY H. PRESTON 2,385,027

STOKER Fil'ed Oct. 29, 1941 6 Sheets-Sheet 2 INVENTOR hERBERT E. mssro'u av H. E. PRESTON STOKER Filed Oct. 29, 1941 Sept. 18, 1945.

'6 Sheets-Sheet 4 INVENTOR HERBERT 5. PRESTON Patented Sept. 18, 1945 STOKER.

Herbert E. Preston, Philadelphia, Pa., assignor, by mesne assignments, to American Engineering Company, Philadelphia, Pa., a corporation of Pennsylvania Application October 29, 1941, Serial No. 416,936

14 Claims.

This invention relates to stoker furnaces, and more particularly to stokers of the multiple retort, underfeed type provided with extension grates or overfeed sections.

One object of the present invention is to provide in a stoker of the stated character, a novel overfeed section whicheffectively feeds the partialiy consumed fuel and refuse toward a place of disposal, the feedin thereof being so effected as to insure complete combustion of the fuel.-

Another object is to provide a generally improved stoker having an underfeed section and an overfeed section, the parts of which being so disposed as to continuously feed the fuel toward a discharge passage through which the ashes pass into a place of disposal from which they may be removed from time to time.

Another object is to provide in a stoker of the stated character an overfeed section which operates to break up large clinker formations, and to progressively feed the partially consumed fuel,

' ashes, and clinker toward a discharge passage.

A further object is to provide an overfeed section so constructed that a multiplicity of uniform, finely divided streams of air may pass therethrough into the fuel bed to insure proper combustion of the fuelas it passes thereover.

A further object is to provide in a stoker of the stated character an extension grate comprising a series of successive sections, each of which is operated to produce a lifting, as well as progressive feeding action of the fuel, thereby breaking up clinker masses and insuring proper combustion, as the fuel and refuse passes toward a place of disposal.

A further object is to provide an extension grate of the stated character'having a series of relatively small grate elements mounted on eccentric means whereby an oscillatory movement is imparted thereto, these sections being provided in rows whereby agitation, as well as feeding of the fuel and refuse is effected as it moved to: wards an ash pocket.

A still further object is to provide an overfeed section consisting of a series of rows of relatively narrow grate elements, the spacing of said grate elements in each of said rows may be readily varied across the Width of said section, to insure the proper supply of air from one end of the section to the other, and thus insuring complete combustion of the fuel.

A still further object is to provide an extension grate of the stated character having a series of rows of relatively small grate elements, cam means for actuating each of the rows of grate elements, the said cams being so disposed that the movement of one row of elements may be varied with respect to the next row to provide the proper amount of agitation of the fuel supported on said grate elements.

A further object is to provide in a stoker of the stated character an extension grate which may be operated by or independently of the operating mechanism of the stoker proper.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings:

Fig. 1 is a longitudinal sectional view taken through one of the retorts of an underfeed stoker showing the structure of the extension grate and its relation to the stoker proper.

Fig. 2 is a partial plan view taken substantially along line 2-2 of Fig 1.

Fig. 3 is a plan view partly in section and with the extension grates removed showing the operating mechanism for the extension grates.

Fig. 4 is an elevational view, partly in section, of the supporting means for the extension grate bars and the cam means for operating thefsame.

Fig. 5 is an enlarged side view of the lowermost row of grate bars showing the operating means therefor.

Fig. 6 is a perspective View of the supporting structure for the row of grate elements provided at the upper end of the extension grate, one grate element being shown in position.

Fig. '7 is a perspective view of one of the intermediate grate bars.

Fig. '8 is a longitudinal sectional view taken through one of the retorts of a stoker showing a modified operating mechanism for the extension grate.

Fig. 11 is a plan view of a still further mod ification of the present invention.

Fig. 12 is a side view taken substantially along line l2-l2 of Fig. 11.

Fig. 13 is a plan view of the structure shown in Fig. 11 with the grate bars removed and with certain parts broken away to show the operating mechanism for the grate bars shown in .Figs. 11 and 12.

Fig. 14 is an elevational view, partly in section, taken substantially along line I4 -I4 of Fig. 13.

Fig. 15 is a perspective view of a group of six grate bars which may comprise a unit, said grate bars being of the type shown in Figs. 11 and 12, and

Fig. 16 is a perspective view of one of the grate bars shown in Fig. 15, a portion thereof being broken away to show its structure.

Referring more particularly to Figs. 1 and 2 of the drawings, the numeral l represents a stoker of the inclined grate multiple retort type comprising alternately disposed retorts 2 and tuyere rows 3. An extension grate or overfeed section 4 is disposed at the rear of the retorts and tuyre rows 2 and 3, respectively, which feeds the partially consumed fuel and refuse toward, and the refuse through a discharge passage 5 provided at the rearmost end of the furnace. The stoker I is disposed between side walls 6 and T of the furnace (Fig. .2) and is bounded at the front end by a wall 8 and at the rearwardly disposed end by a wall 9. Fuel is fed to the stoker from hoppers I disposed exteriorly of the front wall 8 by a series of rams II driven by any suitable power mechanism indicated at I2. The fuel so entering the stoker is fed along the retorts and tuyere rows 3 by pushers I3 which are operatively connected to the power mechanism by any suitable link and lever mechanism indicated generally at I4. Air for combustion purposes is supplied to the underfeed section from a plenum chamber I and to the extension grates from a subplenum chamber I6. Air under pressure is supplied to plenum chambers I5 and i6 by any suitable fan or blower mechanism, not shown.

As shown moreparticularly in Figs. 1 and 2, the extension grate or overfeed section 4, comprises five rows of grate elements II, I8, I9, 28 and 2-1, respectively. These rows of elements, as shown more particularly in Fig. 1, are disposed in overlapping relation and progressively feed the :fuel and refuse toward the discharge passage 5.

The uppermost row of grate elements I! each comprises an elongated body portion Il as shown more particularly in Fig. 6, which is relatively wide at the bottom, as shown at IT, and tapers toward the upper edge 'I'I, thereby presenting "a relatively narrow edge to the fuel supported thereon. The rearwardly disposed end I-I of 62.01]. grate bar I1 is provided with an offset portion 22 which rests upon a grate bar I8 of the next lower row of the series. The forwardly disposed end "23 of each grate bar I! is provided with an irregular opening 24, through which air may pass for cooling purposes. forwardly disposed end 23 is enlarged and has provided at the lower side thereof a notch 25 which engages a transversely disposed bar 28, supported by brackets 2-! secured in any suitable manner to the supporting framework .28 disposed between the extension grate 4 and the underfeed section of the stoker proper. Each bracket 2] is provided with an open ended :slot 2:9 which receives the supporting bar 28. Each bar I! has provided therein an aperture I! for receiving a locking pin. By this means any desired number of grate bars .I] maybe connected into groups.

Each of th grate bars I8, I9, 20 and 2| are substantially identical in structure and accordingly a detailed description of one will suffice for all. For the purpose of illustration, a detailed description of a grate bar I8 wil1 now be given.

As shown more particularly in Figs. 1 and 7,

The'

each grate bar I8 consists of an elongated body IPOItlOIl 32 which terminates at its rearwardly disposed end in a substantially vertical fuel feeding portion I8 The lower extremity of body portion 32 is provided with relatively parallel sides 33 and 34, the side 33 terminating in a bevel portion 35 which extends to the upper edge 36 of the grate bar. The upper edge 36 is substantially arcuate near the forwardly disposed end thereof, as shown at 31, and is provided with a Vertically projecting portion 38 having a vertically disposed surface 39 at the rearwardly disposed end thereof which acts as a fuel feeding surface during operation of the device. The upper edge of bar l8 from surface 39 to the rearmost end is relatively straight, as shown at 40. Each grate bar I8 also comprises a downwardly extending portion M which terminates at its lowermost end in a hook 42 which is adapted to engage the offset portion 43 of a supporting member 44 (Figs. 1 and 5). Each grate bar I8 is also provided with arcuate portions 45 and 46 which in assembly rest upon the upper arcuate surface 4'! of supporting member 44. The under surface of each grate bar I8 also has provided therein a recess 48 which in assembly provides an air space through which draft air may circulate for cooling purposes.

The supporting members 44 for each of the rows of grate bars I8, I9, 28 and 2| are identical in construction, and accordingly a detailed description of one only will be given herein. Referr'ing more particularly to Figs..1, 4 and 5, it is seen that each supporting member 44 consists of the upper arcuate portion 41 which terminates at the sides thereof in offset-portions 43 and 49, the former of which, as heretofore stated, 'is adapted to be engaged by the hooks 42 of the associatedgrate bars. Each supporting member 44 is substantially hollow in construction, as shown more particularly in Fig. 4, and is provided with four bifurcated portions 58, '5I, 52 and 53 which rest upon cams 54, '55, 56 and 51, respectively. The legs 58 and 59 of th end bifurcations 50 and 53, respectively, are longer than those of the intermediate bifurcations and are provided with apertures 60 for receiving strap bolts 6|, the latter of which may be secured in position by any suitable means, such as by the nuts 82, secured to the outermost ends of --the said bolts; As shown in Fig. 5, bolts 6| are slightly'spaced from the lower ends of cams 5'4 and 5! to prevent. binding.

The cams 54, '55, 56 and '5'! are secured in any suitable manner, such as by welding to operating shaft 63. Apertures 64 and 65 are provided in each of the grate bars I8, I9, 28 and 2! for the purpose of securing any given number thereof into groups.

The lowermost grate bars 2I are of substantially the same construction as the intermediate bars I8, I9 and 20, except that each is provided with three vertically disposed fuel feeding faces 39, 39", and ZI, and also with a downwardly extending bifurcated member 66 at th rearwardly disposed end thereof. Members 66 are adapted to receive rods 51 which are held in posi tion by bolts 68 extending through apertures provided at the lower ends of the legs 69 and ID of the'said bifurcations 66. Each rod 81 is pivotally attached to the upper end of a link II which in turn is pivoted to the outer end of an arm I2 secured in any suitable manner to a shaft I3. Shaft 13 may be mounted in any suitable bearings I4 and, 15 provided in side walls 6 and 1, respectively. The left hand end of shaft I3 extends through side wall I and is secured in any suitable manner to a worm wheel I6 which engages a vertically disposed worm gear 11, which in turn may be actuated by any suitable means, such as by a hand crank I8 (Fig. 2). Worm gear TI and worm wheel I may be enclosed within any suitable casing I9. As shown in Fig. 3, the lower- 7 most grate bars 2| are divided into groups of four across the width of the furnace, each group being supported by a rod 61, and is actuated by a respective link II and arm I2.

Referring more particularly to Fig. 5, it will be seen that each supporting member 44 has provided at the right hand side thereof a pair of laterally extending ears 80 through which extend bolts 8|. An angle 82 is provided to hold the outer end of each of the grate bars I8, I9, 20 and 2I in position. As shown in Fig. 5, the upper flange 83 of angle 82 engages the forwardly disposed offset portions 84 of the associated grate bars and the bolts 8| then are tightened. This effectively holds the forward end of each grate bar in position.

The supporting members 44 of grate bars I8, I9, 20 and 2| are operated respectively by shafts 85, 8B, 81 and 63, respectively. Shaft 85 is mounted in any suitable bearings 88 and 89 provided in side walls 6 and I, respectively, and has secured thereto a sprocket wheel 90 which is connected by a chain 9| to a sprocket wheel 92 secured to a drive shaft 93. Drive shaft 93 is mounted in any suitable bearings 94 and 94 provided in side walls 6 and I. The left hand of shaft 93 extends through side wall I and has secured to the outer end thereof a sprocket wheel 95 which is connected by a chain 96 to a sprocket wheel 91 provided on the outer end of the drive shaft 98 of an electric motor 99. Thus, upon actuation of motor 99, a rotary motion is imparted to shaft 93, and consequently to shaft 85 which, through the cams 54, 55, 56 and 5'! mounted thereon, imparts an oscillatory movement to the supporting members 44 and the grate bars I8 supported thereon. Shaft 30 is mounted in bearings 85' and 86", provided in side walls 6 and I, respectively, and also has secured thereto a sprocket wheel I 00 which is connected by a chain IM to a sprocket wheel I02 secured to shaft 93. Shaft 81 is mounted in bearings 81' and 81", and also has a sprocket wheel I03 secured thereto which is connected to a third sprocket wheel I90 provided on shaft 93 by a chain I05. Shaft 83 is mounted in bearings 63' and 63", and likewise has secured thereto a sprocket wheel I96 which is operatively connected to a fourth sprocket wheel I01 provided on shaft 93 by a chain I08. Accordingly, upon operation of motor 99, a rotary motion is imparted to shafts 85, 80, 01 and 63, and consequently an oscillatory movement is imparted to the grate bars I8, I9, 20 and 2! which results in agitation and feeding of the fuel supported thereon toward the discharge passage 5.

As shown in Fig. 1, rear wall 9 comprises a series of fluid conducting tubes I I0, secured at their lower ends to a header III provided exteriorly of the lower portion H2 of rear wall 9.

These tubes extend forwardly and upwardly, as

shown at H3, and then vertically, as shown at II 4, and may terminate in a boiler, not shown. Header III may also be operatively connected to the boiler. The passage 5, as shown in Fig. 1, is

bounded at the lower end by grate bars 2|, and

at the upper end by the inclined portion H3 of tubes H0. The sides of the passag are bounded by the side walls I3 and I of the furnace. The depth of passage 5 may be varied by simply actuating grate bars 2| toward or from tubes H0. In the event that it should be desired to dump the ashes, grate bars 2| are actuated to their lowermost position of adjustment. The'ashes supported on the grate bars 2I then gravitate into a pit I I5 from which they may b removed from time to time by any suitable means.

The grate bars of each of the rows I'I, I8, I9, 20 and 2| are spaced apart slightly to provide openings for draft air. These spaces may be varied from front to rear of the extension grate in order to permit sufficient quantities of air to enter the fuel bed to insure complete combustion of the fuel. The spacing of these grate bars may be effected by sliding them laterally on their respective supporting members 44, and then securing them in position by tightening bolts 8|.

Figs. 8, 9 and 10 illustrate another embodiment of the present invention. This construction is generally similar to that just described, except that the individual extension grate bars of the extension grate or overfeed section 4' of thestoker I differ slightly in construction from those previously described. The operating mechanism also differs from that of the structure shown in Fig. 1.

As shown in Fig. 8, stoker I also consists of a series of alternately disposed retorts 2' and tuyere rows 3. Fuel is fed to the stoker I' from hoppers I0 by a series of rams II driven by any suitable power mechanism I2. Pushers I3 provided in the bottom of each retort underfeed the fuel to the overfeed or extension grate section 4' which, in turn, feeds the refuse through the discharge opening 5 provided at the rear of the stoker. The pushers I3 of each retort have secured to the forwardly disposed ends thereof connecting rods I20 which are pivotally connected at their forward ends to a lever I2I pivoted intermediate its ends to the supporting framework I22, as shown at I23. The upper end of lever I2I is pivoted to the outer end of a link I24, the inner end of which being pivotally connected to a rod I25 provided centrally of ram II'. Link I24 and lever I 2| are pivotally connected to one end of a pitman I26, the opposite end of which being connected to the crank shaft I 21 of operating mechanism I2.

' The lower end of lever I2I has pivotally conposition shown in Fig. 9. Arm I29 has secured thereto a hub or sleev I35 which surrounds the slotted portion of the shaft I30 and retains-the balls I32 in position.

From the foregoing description, it is seen that when arm I29 is turned in a counter-clockwise direction (Fig. 9), the balls tend to fIlOVB to the left toward the narrow portion of slots I 3 I, thereby causing binding of the hub to shaft I 30 and consequently the latter moves with arm I29. When arm I29 is actuated in a clockwise direction, the balls tend to move toward th enlarged,

portion of slots I3I, thereby releasing the binding action and permitting arm I 29 to move independently of shaft I30. I

Shaft I 30 has secured thereto four sprocket I of the extension grate or overfeed section 4'.

wheels I30 similar to sprocket wheels 92, I04, I07! and I02 of the construction shown in Figs. 1 to 3,only one of which is shown. These sprocket w-heels I36 are connected to sprocket Wheels 137, I38, I39 and I 40 by chains MI, I42, I 43 and 144, respectively. Sprocket Wheels I31, 138, I39 and I40 are mounted respectively on shafts I45, I46, 14-! and I49, on which are respectively mounted cams I49, I50, I:I and 1:52.

Extension grate 4' also consists of five transverse rows of grate bars I i, I8, I9, 20 and 2I". Grate bars II are identical in construction to the grate bars I! already described, and accordingly, a detailed description thereof need not be given. Grate bars I8, I9','20 and 2| are substantially identical in construction and acoordingly a detailed description of one will suffice for all. For the purpose of illustration, a detailed description of one of the grate bars I8 will now be given.

I As shown more particularly in Figs. 8 and 10, each grate bar I18 comprises an elongated body portion I55 having an upper edge I56 which terminatesin an offset portion I51 intermediate the ends providing a substantially vertical fuel feeding face 158. The sides I59 and I00 of body portion I55 are substantially parallel, the side I60 terminating at its upper end in a tapered portion IBI thereby providing a relatively narrow upper edge I56 to the fuel supported thereon. The forwardly disposed end hi2 of each grate bar is provided witha depending bifurcated portion I63, the upper portion I64 of which being of arcuate construction and having substantially the same curvature as cam M9, and which in assembly restsupon said-cam. The legs I65 and I66 extend slightly below the lower extremities of cam I49 and are provided with aligned apertures I61 for receiving retaining bolts I68 which hold the grate bars in position. The end of each grate bar I8 terminates in a vertically disposed fuel feeding portion I09.

From the foregoing description, it is seen that upon operation of the power means I2, by virtueof the clutch mechanism between arm I29 and shaft I30, a progressive movement is imparted to shaft I30 which through the chain and sprocket mechanisms connecting shaft I30 with shafts I45, I46, I41 and I48 oscillatory movement is imparted to the grate bars I8, I9, 20' and 2| In order to permit draft air to pass into the fuel bed, grate elements I 8, I9, 20 and 2 I, may be spaced apart, the width of the spaces being governed by the quantity .of air necessary to insure proper combustion of the fuel. Spacing washers H0, or any other suitable means, may be provided to properly space the grate bars.

Each of the lowermost grate bars 2-I' has provided at the lower end thereof a bifurcated portion 66' similar to the portion 69 of grate bars 2I for receiving rods 61' which are retained in position by bolts 68'. Rods 9'! are, as previously described, attached to the upper end of links II, the lower ends of which being connected to arms I2- secured .to a shaft l's. Shaft I3 is adjusted by mechanism similar to that shown in Figs. 2 and 3, or by any other suitable mechanism for the purpose of adjusting grate bars 2 I Each of the lower grate bars 2| in addition to vertical fuelfeeding faces I58 and IE9 has a third feeding face I58.

Figs. 11 .to 16 illustrate a further embodiment of the present invention. This construction comprises an extension grate II" which also consistsof five rows-of grate bars II", I8", I9, 20 and 2'-I"-. Grate bars II" are similar in all respects to grate bars I'I, previously described and accordingly a detailed description thereof will not be given.

Grate bars I8", I9", 20" and 2|" are pivotally connected to the upper ends of levers I12, I19, I14 and I15, respectively, which levers are secured to shafts I76, I11, I18 and H9, respectively.

The grate bars of each row may be connected into groups, as shown in Fig. 15. One lever I12, I13, II I or H5 is required for each group of grate bars in the respective rows, and therefore the number of such levers employed is governed by the number of groups of grate bars across the extension grate.

Shafts I15, I71, I19 and I19 have respectively secured thereto downwardly extending arms I80, I8I, I82 and I93. To enable simultaneous operation of shafts H9 and I18 arms I80 and I82 are connected by a link I84, while to enable simultaneousoperation of shafts Ill and H9 arms IIlI and I83 are connected by a link I85. Shaft I'I9 also has secured thereto a downwardly extending arm I 96, to the lower bifurcated end I8'I of which is pivotally connected one end of a link I89. The opposite end of link I88 is connected to the lower bifurcated end I89 of a lever I90, which is pivoted at the upper end thereof to brackets I9I' and I92. A rod I93 is operatively connected at one end thereof to lever I90 intermediate the ends of the latter. The other end of rod I93 may be connected to any suitable operating mechanism such as to a lever I2I shown in Fig. 8, which in turn may be connected to any suitable power mechanism. Shaft I10 has also secured thereto an arm I94 to the lower bifurcated end I95 of which is attached one end of a link I96.

The other end of link I96 is pivotally connected to the lower bifurcated end I97 of a lever I98 pivoted intermediate its ends on a rod I99, supported at the opposite ends thereofin brackets 290 and 20L The upper end of lever I98 has secured thereto one end of an operating rod 202, the opposite end of which, like rod I93, may be connected to any suitable operating lever such as the operating lever I2I shown in Fig. 8, which in turn may be operatively connected to a driving mechanism, such as the power mechanism I2. Thus upon actuation of rod I93, a rocking movement will be imparted to shaft I I9, which in turn will cause an oscillating movement of the grate bars 25". Shaft IT? by virtue of its connection with shaft I'I9 will be simultaneously operated causing a similar movement to be imparted to grate bars I9. It is also seen that upon actuation of rod 292, an opposite movement will be imparted to shafts I73 and I 56, casing an oscillatory movement to be imparted to grate bars 20 and I9". If rods I93 and 202 are operated simultaneously, and in the same direction, grates I9 and 20" will move in a direction opposite to that of grates I9 and 2I".

The individual grate bars I8, I9", 20" and '2!" are substantially identical in construction and accordingly a description of one will suffice for all. Accordingly, a description of grate bars I8" will now be given.

As shown in Fig. 15, a group of six bars are provided; these bars may be'secured together and operated as a group. Each grate bar I8 comprises a relatively flat upper fuel supporting surface 295 having at the sides thereof .-a pair of downwardly extending flanges 296 and 207,

and at its rearwardly disposed end a vertical flange 208 which constitutes a fuel feeding surface. The forwardly disposed end of each bar I8" is provided with a pair of downwardly extending ears 209 having aligned apertures 2ID provided therein'for receiving a pin 2| I, thereby enabling pivotal attachment of the bars l8" to leversllZ, and the connection of several grate bars intogroups.

Each grate bar 2|" is provided with a bifurcated portion 66" at the lower end thereof connected to. a link 'H" which in turn is connected to an arm 12" secured to a transverse shaft 13", Which is adjusted by a mechanism similar to that shown in Fig. 3, and previously described in detail herein.

The grate bars l1", I8", I9", 20" and 2|" may be spaced slightly apart to provide passages for draft air, the width of these spaces being determined by the quantity of air necessary to insure complete combustion of the fuel supported thereon. It is also seen that the number of grate bars connected into groups may differ from that illustrated in Fig. 15. By connecting the grate bars into groups fewer operating levers I72, I13, I14 and I15 are required. The groups maybe connected by extending the pins 2| I through the apertures 210 of the desired number of grate bars. The rearwardly disposed ends of the grate bars rest at all times upon the bars of the next lower row ,of the series.

From the foregoing description of the different embodiments of the present invention it is seen that effective and highly efficient constructions have been provided. The structures are such that the different rows of grate elements may operate in any desired predetermined sequential order. For example, it may be desired to have one row of grate elements move downwardly, while the adjacent rows move upwardly. This may be done by simply disengaging the driving connection between shaft 93 and one of the shafts 85, 86 and 81 or 63 f, the construction in Fig. l, and then adjusting the shaft to the desired position. The driving connectionbetween that shaft and drive shaft 93 is then reestablished. Groups of grate bars in the same rows'm'ay operate differently by so arranging the cams; It is also seen that in the construction shown in Figs. 11 to 16 other of the rows than those connected by links I84 and I85 maybe connected without departing from the invention. For example, the grate bars I 8 and 2| may be connected for simultaneous movement, while bars I9 and 20 may also be connected for simultaneous movement.

It is therefore to be understood that it is not intended to limit the invention to the specific embodiments herein shown and described, but only by the scope of the claims which follow.

What is claimed is:

1. An overfeed section for stokers comprising a series of rows of grate bars, said rows of grate bars being disposed in substantially parallel relation longitudinally of said overfeed section, the grate bars of each of said rows being mounted in spaced relation forming a series of passages for draft air, means for pivotally supporting the grate bars of one of said rows, cams for supporting the grate bars of said other rows, means for operatively connecting said cams to said grate bars, and means for operating said cams whereby oscillatory movements are imparted to said rows of grate bars.

2. An overfeed section for stokers compris ing a series of rows of grate bars, said rows of grate bars being disposed in substantially parallel relation longitudinally of said overfeed section, the grate bars of each of said rows being mounted in spaced relation forming a series of passages for draft air, means for pivotally supporting the grate bars of one of said rows, cams for supporting the grate bars .of said other rows, means for operatively connecting said cams to said grate bars, means for operating said cams whereby oscillatory movements are imparted to said rows of grate bars, andmeans for Vertically adjusting the grate bars of one of said rows.

3. An overfeed section for stokers comprising a series of rows of grate bars, said rows of grate bars being disposed. in substantially parallel relation, the grate bars of each of said rows being mounted in spaced relation forming a series of passages for draft air, each of said grate bars having a bifurcated portion. provided at one end thereof, cam means adapted to engage the said bifurcated portions, means for. retaining said cam means in engagement with said bifurcated portions whereby upon operation of said cam means orbital movements are imparted to said rows of grate bars, means operatively connecting said cam means for simultaneous movement, and operating means for said cam means.

4. An overfeed section for stoker furnaces comprising a series of rows of grate bars dis- I posed in substantially parallel relation longitudinally of said overfeed section, each of said rows of grate bars extending from the real-most of said rows being disposed in overlapping relation, a shaft adjacent each of said rows, cam means secured to each of said shafts, cam followers operatively connected to said cam means, means for detachably securing said grate bars to said cam followers, and opera-ting means for said cam means.

5. An overfeed section for stoker furnaces comprising a series of rows of grate bars disposed in substantially parallel relation longitudinally of said overfeed section, said rows of grate bars being disposed in overlapping relation, supporting means for each of said rows of grate bars including cam means, means operatively connecting said grate bars to said cam means whereby upon operation of the latter orbital'movements will be imparted to said rows of grate bars, and operating means for said cam means.

6. An overfeed section for stoker furnaces comprising a series of rows of grate bars disposed in substantially parallel relation longitudinally of said overfeed section, said rOWs of grate bars being disposed in overlapping relation, supporting means for each of said rows of grate bars including cam means, means operatively connecting said grate bars to said cam means whereby upon operation of'the latter orbital movements will be imparted to said rows of grate bars, operating means for said cam means, means operatively connecting said cam means for simultaneous movement, and power means for actuating said cam means.

'7. An overfeed section for stoker furnaces comprising a series of rows of grate bars disposed in overlapping relation, a shaft disposed beneath each of said rows of grate bars, cam means of substantially arcuate construction secured to each of said shafts, cam followers operatively connected to each of said cam means, each of said cam followers comprising an elongated body portion having a substantiallyarcuate upper surface adapted to support said grate bars, means extending outwardly from the forwardly and rearwardly disposed sides of said body portion adapted to engage locking means operatively connected to said grate bars to hold the latter in operative position, and a series of spaced bifurcations depending from said body portion, eachof said bifurcations having a rounded upper surface adapted to engage said cam means whereby upon operation of said oam means, said cam followers are actuated in orbital paths to effect vertical as well. as longitudinal movements of said rows of grate bars.

8. A cam follower comprising an elongated body portion having. a substantially arcuate upper surface, means extending outwardly from the forwardly and rearwardly disposed sides of said body portion adapted to be engaged by locking means for grate bars, and a series of spaced bifurcations depending from saidbody portion adapted to receive cam means.

9. A cam follower comprising an elongated body portion having a substantially arcuate upper surface, means extending outwardly from the forwardly and rearwardly disposed sides of said body portion adapted to be engaged by locking means for grate bars,- a series of spaced bifurcations depending from said body portions adapted to receive cam means, and the legs of certain said bifurcations being longer than those of the others and having apertures provided at the lower ends thereof adapted to receive means for retaining the said cam follower in engagement with the cam means.

10. An overfe'ed grate construction for stokers comprising a series of rows of grate bars, said rows of grate bars being disposed in substantially parallel relation longitudinally of said overfe'ed section, cam means for each of said rows of grate bars, means operatively connecting said rows of grate bars to said cam means whereby upon operatio'n of the latter orbital movements are imparted thereto, means operatively connecting said cam means for simultaneous movement, and operating means for said cam means.

11'. An overfeed grate construction for stoker furnaces comprising a series of rows of grate bars, said rows of grate bars being disposed in substantially parallel relation longitudinally of said-grate construction, each of the said rows of grate bars extending fromtherearmost row of said series being disposed in overlapping relation with an adjacent row of grate bars, cam means for each-of said rows of grate bars, means operatively connecting said rows of grate bars to their respective cam means whereby upon operation of the latter orbital movements are imparted thereto, means operatively connecting said cam means for simultaneous movement, and operating means for said cam means.

12. An overfeed grate construction for stoker furnaces comprising a series of rows of grate bars, said rows of grate bars being disposed in substantially parallel relation longitudinally of said grate construction, each of the said rows of grate bars extending from the rearmost row of said series being disposed in overlapping relation with an adjacent row of grate bars, cam means for each of said rows of grate bars, means operatively connecting said rows of grate bars to their respective cam means whereby upon operation of the latter orbital movements are imparted thereto, means operatively connecting said cam means for simultaneous movement, operating means for said cam means, and means for vertically adjusting one end of the grate bars of said rearmos row to vary the effectiveness thereof. a

13. An overfeed grate construction for stoker furnaces comprisin a series of rows of grate bars, said rows of grate bars being disposed in substantially par'ahel relation longitudinally of said grate construction, each of the said rows of grate bars extending from the rearmost row of said series being disposed in overlapping relation with an adjacent row of grate bars, cam means for each of said rows of grate bars, means operatively connecting said rows of grate bars to their respective cam means whereby upon operation of the latter orbital movements are imparted thereto, means operatively connecting said cam means for simultaneous movement, operating means for said cam means, an additional row of grate bars disposed adjacent to and arranged in overlapping relation with the foremost of said rows of grate bars of said series, and means for pivotally supporting said additional row of grate bars.

14. An overfeed section for stoker furnaces comprising a series of rows of grate bars disposed in overlapping relatiorna shaft associated with each of said rows of grate bars, cam means secured to said shafts, cam followers mounted on said cam means, each'of said cam followers comprising an elongated body portion having a substantially arcuate upper surface adapted to support a number of grate bars, means extending from the sides of the said body portion disposed toward the front and rear of said overfeed section adapted to engage locking means operatively connected to said grate bars for retaining the latter in operative position, and a series of spaced bifurcated portions depending from said body portions, each of said bifurcated portions having a rounded upper surface adapted to engage an associated cam means, operating mechanism for said cam means whereby upon operation of the latter said cam followers are actuated in orbital paths thereby effecting vertical. as well as longitudinal movementsof said rows of grate bars, and means for vertically adjusting the grate bars of the rearmost of said rows to vary the effectiveness thereof.

HERBERT E. PRESTON. 

